Spark plug



March 20, 1928.

G. N. BARCUS SPARK PLUG Filed June 20, 1927 nnnmm lllllii:

gwvenkoz Patented Mar. 20, 1928.

UNITED STATES GEORGE N. BARCUS, 0F ANDREWS, INDIANA.

SPARK PLUG.

Application filed June 20, 1927. Serial No. 200,150.

My invention relates to a spark plug and process of manufacturing thesame and it 1s an object of the invention to provide a plug in whichpressure difl'erences on the gaskets are greatly reduced thuspr0p0rtionately reducing the cause of leakage, and a further object ofthe invention is in manufacturing to reduce the breakage of insulatorsand to prevent localized stresses on said insulators, all as will behereinafter more fully described and claimed.

Referring to the accompanying drawings which are made a art hereof andon which similar reference c aracters indicate similar parts,

Figure 1 is a side elevation of the spark plug constructed in accordancewith my invention,

Figure 2, a part side elevational, part sectional view showing inoutline the rotating spindles for compressing parts of the plug inassembling, and

Figure 3, a fragmentary detail section of the sleeve shown in Fig. 2illustrating the method in which the same is rolled or shrunk onto thebody member.

In the drawings reference character 10 indicates the body member orshell of a spark plug having its lower end threaded for engagement withthe cylinder wall of an internal combustion engine and having an annularflange 11 adapted'to seat on such cylinder wall for limitlng themovement of the body into the cylinder wall. The upper end of the body10 is provided with an inclined or flared end portion 12 which forms aseat for an insulator 13 of conventional construction. The insulator 13is provided with a relatively short tapered upper end portion and aslightly longer tapered lower end portion between which is disposed asubstantially cylindrical intermediate portion having upper and lowerinclined shoul' ders 14 and 15. The insulator 13 is also provided with acentral electrode of conventional construction which may be held inplace in the insulator by lock-nuts 16 or in any other well knownmanner.

Means is provided for binding the insulator tightly against the end ofthe body member or shell 10 and such means comprises a shell or sleeve17 having a shoulder 18 formed complementary to the shoulder 14 of theinsulator and provided with a lower end 19 ofa reduced thickness so thatit may be easily rolled or spun into an annular channel or slot 20 onthe body member or shell 10.

A gasket 21 is disposed between the shoulders 14 and 15 and thecooperatingabutting surfaces in order to form a gas tight joint when theparts are in assembled relation. The bottom of the annular channel orslot 20 of the body 10 is preferably'knurled at 22 so that when thesleeve and body are pressed together they will be secured in fixedrelation to each other so that upon rotation of the sleeve 17 by meansof a wrench or other suitable tool the body 10 will also be rotated.

In assembling the parts of the plug, the insulator 18 is provided with agasket at each side of its enlarged cylindrical portion, the lowergasket serving to seal the joint between the upper inclined or flaredend'o'f the body 10 and the shoulder 15 of the insulator, and the uppergasket being adapted to seal the joint between the complementary portionof the sleeve or shell 17 and the inclined portion 14 of the insulator.The parts are placed between rotating spindles 23 and 24, which areshown in dotted lines in Fig. 2, and force is applied for pressing thesleeve 17 upon the body 10 of the plug for uniformly compressing thegaskets 21 after which a roller 25, shown in dotted lines in Fig. 3, isapplied against the thin lower portion of the neck or reduced lower endof the sleeve 17 by means of which the said sleeve is spun or rolledinto the annular channel or slot 20 around the body of the plug. Thisrolling operation causes the thin ortion of the sleeve or thread as itenters t e channel 20 to become elongated and fit tightly between thesides of the channel or slot which causes a tight joint with theinterior of the sleeve snugly engaging the knurled surface 22. Pressureapplied for forcing the sleeve or shell 17 upon the body 10 is only inan axial direction and the insulator is held in place solely by suchaxial pressure while at the same time the rolling is accomplished inspaced relation to the enlarged portion of the insulator, therebypractically eliminating the breakage of insulators in manufacture aswell as the elimination of localized stresses on the insulator while atthe same time the gaskets are subjected to sufficient pressure so thatthere is practically no chance for leakage around the same.

It will be obvious to those skilled in the art thatvarious changes maybe made in my device without departing from the spirit of my invention,and I, therefore, do not limit myself to What is shown in the drawingsand described in the specification, but only as set forth in theappended claims.

Having thus fully described my said invention, What I claim as new anddesire to secure by Letters Patent, is:

1. A spark plug comprising a body having an inclined upper extremity, anexternal an nular channel below said extremity, a f "ket resting on theextremity of said bod an insulator having an enlarged portion resting onsaid gasket, a gasket disposed on the opposite side of the enlargedportion of the insulator, and a sleeve having an internal flange restingon said last mentioned gasket and having its opposite end spun into saidannular channel on said body, substantially as set forth.

2. The process of making aspark l g comprising telescoping a sleeve overthe bony of a plug, to compress an insulator therebetween, pressing saidparts together in an axial direction, and spinning the inner end of thesleeve tightly into engagement with the body of the plug, substantiallyas set forth.

3. A spark plug comprising a min body having one end threaded forengagement with a cylinder wall and having its other end inclined forengagement with a gasket, :1 channel formed about said body, aninsulator resting on the upper end of said body, a sleeve engaging saidinsulator and having a reduced portion fitting snugly about said body,substantially as set forth.

at. lhe process of making a spark plug comprising telescoping a sleeveover a body of the plug, with an'insulator tlierebetween, pressing saidbody and sleeve together in an axial direction and rolling theteleseoped end of the sleeve tightly into engagement with said body,substantially as set forth.

5. A. spark plug comprising a body having its lower end portion formedfor engagement with a cylinder wall, an insulator extending through saidbody, a sleeve engaging said insulator and secured on said body, saidbody being provided with an annular reduced knurled portion, said sleevellttVlllg a reduced annular portion disposed in said annular knurledportion, substantially as set forth.

in witness whereof, I have hereunto set my hand at Andrews,lndiana thisth day of May, A. D. nineteen hundred and twenty-

